DESCRIPTION: In this application the principal investigator proposes to examine synaptic inputs, membrane properties and the distribution NMDA receptors on cells in the cat superior colliculus that contain calbindin (CB), parvalbumin (PV), nitric oxide synthetase (NOS). The principal investigator believes that these cell groups offer an opportunity to examine the relationships between chemical content, afferent input and physiology in a well- characterized system.